Modular total knee arthroplasty system and method

ABSTRACT

A modular system for total knee arthroplasty includes a modular trial implant assembly. The modular implant assembly includes an elongate shaft configured for insertion into an elongate cavity in a bone, a reamer removably coupleable to the elongate shaft via a connection that allows the reamer to rotate while the elongate shaft remains in a substantially fixed angular orientation. The reamer has an outer surface that tapers toward the distal end configured to form a tapered cavity in an end of a bone in which the reamer is inserted and rotated. The modular trial implant assembly further includes a trial implant removably coupleable to a proximal end of the reamer. A modular final implant assembly includes an elongate stem, a tapered body and an implant body, each having a size and shape that can substantially correspond to a size and shape of the elongate shaft, the reamer and the trial implant, respectively.

CROSS-REFERENCE TO RELATED APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57 andshould be considered a part of this specification.

BACKGROUND Field

The present invention relates to a system and method for kneereplacement surgery and more particularly to a modular total kneearthroplasty system and method for use in primary and revision kneereplacement.

Description of the Related Art

Total or partial knee replacement is very common, for example to treatconditions such as arthritis or treat injuries to the knee joint (e.g.,from trauma, accidents, sport injuries, etc.). Total knee arthroplastyinvolves implanting a first prosthetic device on the distal end of thefemur and a second prosthetic device on the proximal end of the tibia,where the first and second prosthetic devices replace the naturalarticulating bone surfaces of the knee joint (e.g., femoral condyles).Such surgical procedures involve cutting sections of the femur and tibiato accommodate the prosthetic devices in proper alignment, and can becomplex and time consuming.

In some cases, it is necessary to perform a knee replacement revisionsurgery to replace the previously implanted knee prosthetic devices. Forexample, the previously implanted knee prosthetic devices may loosenover time, for example, from the production of wear debris, infection,or fracture. Revision surgery is typically more complicated and timeconsuming than an initial knee replacement surgery because the surgeonmust remove the previously implanted device, which was cemented into thebone or has existing bone into the device. In addition, once the surgeonremove the implant, there is less bone remaining for fixation of therevision implant.

SUMMARY

In accordance with one aspect of the invention, an improved total kneearthroplasty system and method is provided that simplifies the processof delivering a primary or revision knee replacement implant, as well asto replace an existing knee replacement implant, and makes suchprocesses less time consuming.

In accordance with one aspect, a modular system for total kneearthroplasty is provided. The system comprises a modular trial implantassembly. The modular implant assembly comprises an elongate shaftconfigured for insertion into an elongate cavity in a bone. The modulartrial implant assembly also comprises a reamer that extends between aproximal end and a distal end, the reamer being removably coupleable toa proximal end of the elongate shaft via a connection that allows thereamer to rotate while the elongate shaft remains in a substantiallyfixed angular orientation. The reamer has an outer surface that taperstoward the distal end of the reamer. The outer surface further has aplurality milling elements extending between the proximal and distalends of the reamer about the circumference of the reamer, the millingelements configured to form a tapered cavity in an end of a bone inwhich the reamer is inserted and rotated. The modular trial implantassembly further comprises a trial implant removably coupleable to aproximal end of the reamer. The elongate shaft is configured to provideangular orientation but not rotational stability when inserted into theelongate cavity, and wherein the reamer is configured to providerotational and axial stability in the tapered cavity.

In accordance with another aspect, a modular system for total kneearthroplasty is provided. The system comprises a modular trial implantassembly. The modular implant assembly comprises an elongate shaftconfigured for insertion into an elongate cavity in a bone. The modulartrial implant assembly also comprises a reamer that extends between aproximal end and a distal end, the reamer being removably coupleable toa proximal end of the elongate shaft via a connection that allows thereamer to rotate while the elongate shaft remains in a substantiallyfixed angular orientation. The reamer has an outer surface that taperstoward the distal end. The reamer comprises a plurality of sequentiallynestable portions releasably coupleable with each other to define atapered shape, where a maximum outer diameter of the tapered shape isdefined by the last of the sequentially nestable portions that arecoupled to each other. The plurality of sequentially nestable portionsare configured to rotate as a single unit when assembled together. Theouter surface further has a plurality milling elements extending betweenthe proximal and distal ends of the reamer about the circumference ofthe reamer, the milling elements configured to form a tapered cavity inan end of a bone in which the reamer is inserted and rotated. Themodular trial implant assembly further comprises a trial implantremovably coupleable to a proximal end of the reamer. The elongate shaftis configured to provide angular orientation but not rotationalstability when inserted into the elongate cavity, and wherein the reameris configured to provide rotational and axial stability in the taperedcavity.

In accordance with another aspect, a modular kit for total kneearthroplasty is provided. The kit comprises a plurality of elongateshafts configured for insertion into an elongate cavity in a femur ortibia bone, each of the elongate shafts differing in one or both oflength and outer diameter. The kit also comprises a plurality of taperedreamers differing in one or both of length and maximum outer diameter,the reamer having an outer surface with a plurality milling elementsextending about the circumference of the reamer. The kit also comprisesa plurality of trial implants of different sizes, wherein each of thetrial implants is coupleable to a proximal end of each of the taperedreamers, which is coupleable to a proximal end of each of the elongateshafts to assemble a trial implant assembly.

In accordance with another aspect, the modular kit further comprises aplurality of elongate stems configured for insertion into an elongatecavity in a femur or tibia bone, each of the elongate shafts differingin one or both of length and outer diameter, a plurality of tapered conebodies differing in one or both of length and maximum outer diameter anda plurality of implants of different sizes. Each of the implants iscoupleable to a proximal end of each of the tapered cone bodies, whichis coupleable to a proximal end of each of the elongate stems toassemble a final implant assembly. Optionally, the plurality of elongatestems, plurality of tapered cone bodies and plurality of implantssubstantially correspond in size and shape with the plurality ofelongate shafts, plurality of tapered reamers and plurality of trialimplants, respectively. Optionally, at least one of the plurality oftapered cone bodies has an outer surface with a plurality of fluteelements extending about the circumference of the tapered conical bodyto define a tapered fluted conical body. Optionally, at least one of theplurality of tapered cone bodies has an outer surface that is porous.Optionally, at least one of the plurality of tapered cone bodies has anouter surface that is rough.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a side view of a knee joint.

FIG. 2 is a schematic view of a front view of a knee joint.

FIG. 3 is a schematic side view of one embodiment of a reaming assembly.

FIG. 4 is a schematic side view of another embodiment of a reamingassembly.

FIG. 5A is a schematic side view of one embodiment of a reaming cone.

FIG. 5B is a schematic top view of the reaming cone of FIG. 5A.

FIG. 6A is a schematic side view of another embodiment of a reamingcone.

FIG. 6B is a schematic top view of the reaming cone of FIG. 6A

FIG. 7 is a schematic side view of another embodiment of a reaming cone.

FIG. 8 is a schematic side view of another embodiment of a reaming cone.

FIG. 9 is a schematic proximal end view of a cut tibia bone with areaming cone therein.

FIG. 10 is a schematic distal end view of a cut femur bone with areaming cone therein.

FIG. 11A is a schematic side view of a cut distal end of the femur bonewith the reaming cone therein prior to installation of a trial femoralknee implant.

FIG. 11B is a schematic side view of a cutting guide disposed at thedistal end of the femur to cut one or more planar surfaces toaccommodate an implant.

FIG. 12 is a schematic side view of the assembly in FIG. 12 afterinstallation of the trial femoral knee implant.

FIG. 13 if a front view of the assembly in FIG. 12 after installation ofthe trial femoral knee implant.

FIG. 14 is a schematic side view of a cut proximal end of the tibia bonewith the reaming cone therein after installation of the trial tibialknee implant.

FIG. 15 is a schematic side view of a device for removing a kneeimplant.

FIG. 16 is a schematic block diagram of a kit for a trial implantassembly and kit for a final implant assembly.

FIG. 17 is a block diagram showing a method of installing a kneeimplant.

FIG. 18 is a block diagram showing a method of removing a knee implant.

DETAILED DESCRIPTION

FIGS. 1-2 shows a schematic side and front view, respectively of a humanknee joint 100, which includes a distal end 12 of a femur 10, a proximalend 22 of a tibia 20, and a patella 30. Total knee arthroplasty (TKA)involves removal of at least a portion of the distal end 12 of the femur10 and at least a portion of the proximal end 22 of the tibia 20 andimplantation of prosthetic femoral and tibial components, as describedfurther below.

FIG. 3 shows one embodiment of an assembly 300 that can be used during atotal knee replacement or total knee revision surgical procedure, asfurther discussed below. The assembly 300 can include an elongate shaftor stem 310 that can be inserted into the bone. In the illustratedembodiment, the assembly 300 is schematically shown disposed in thetibia 20. However, the assembly 300 can also be used in femur 10. Theelongate shaft 310 extends between a proximal end 312 and a distal end314 and has an outer surface 316. Optionally, the elongate shaft 310 canbe cylindrical in shape (e.g., have a circular transversecross-section), conical (e.g., circular in transverse cross-section butwith decreasing cross-sectional area as to crease a taper in theorthogonal plane), or splined/fluted (e.g., have a star-like transversecross-section). The outer surface 316 can optionally be a smoothsurface. As used herein, “smooth” is intended to have its ordinarymeaning (e.g., free from perceptible projections, lumps orindentations); in connection with orthopedic components, “smooth” ismeant to refer, for example, to a surface that is not fluted or hasridges protruding from it, so the component does not provide rotationalstability. In the illustrated embodiment, the elongate shaft 310 extendsalong an axis X that generally coincides with (e.g., is parallel to, iscoaxial with) a central axis of the tibia 20 (e.g., where the tibia 20extends in a normally linear manner such that the axis X of the elongateshaft 310 intersects a transverse plane at an ankle A at the distal endof the tibia 20 substantially at a 90 degree angle). With respect to thefemoral implant, elongate shaft 310 extends along an axis X thatgenerally coincides with (e.g., is parallel to, is coaxial with) acentral axis of the femur 10 (e.g., where the femur 10 extends in anormally linear manner such that the axis X of the elongate shaft 310intersects a transverse plane at a hip at the proximal end of the femur10 substantially at a 90 degree angle). In one embodiment, the elongateshaft or stem 310 is substantially fixed within the bone (e.g., withinthe tibia 20) so that it does not rotate within the bone during theprocedure. Optionally, the elongate shaft 310 can have a length ofbetween about 25 mm and about 200 mm and a diameter of between about 10mm and about 30 mm. However, the elongate shaft 310 can have othersuitable dimensions. The elongate shaft 310 can define a majority (e.g.,greater than 50%, greater than 60%, greater than 75%, greater than 80%,etc.) of the length of the assembly 300.

With continued reference to FIG. 3, the proximal end 312 of the elongateshaft 310 can removably couple with a reamer component 320, optionallyvia a bearing connection 323 (e.g., rolling element bearing, such as onewith an inner race that couples with the proximal end 312 of theelongate shaft 310 and an outer race that couples with the reamer 320,where the inner and outer races rotate relative to each other). Inanother embodiment, the connection 323 can be a boss that allowsrotational movement between the reamer component 320 and the elongateshaft 310, so that the reamer 320 can rotate while the elongate shaft310 remains in a substantially fixed angular orientation. In oneembodiment, the proximal end 312 of the elongate shaft 310 can have across-sectional shape (e.g., hexagonal, pentagonal, square) thatsubstantially matches a shape of an opening in the bearing connectionthat receives the proximal end 312. Accordingly, the reamer 320 canrotate without rotating the elongate shaft 310. The reamer 320 canextend between a proximal end 324 and a distal end 322. In theillustrated embodiment, the reamer 320 has a tapered cone shape so thatthe outer surface 326 of the reamer 320 tapers from the proximal end 324toward the distal end 322. The outer surface 326 of the reamer 320 canhave one or more milling elements 327 (e.g., ridges) that allow thereamer 320 to create a cavity in the bone having a corresponding shapeas the reamer 320. In the illustrated embodiment, the tapered coneshaped reamer 320 can be rotated to form a tapered cone shaped cavity inthe proximal end 22 of the tibia 20.

The proximal end 324 of the reamer 320 can have a connector 328 shapedto couple with a corresponding end of a shaft 410 that can be chucked toan orthopedic tool (manual or electric), such as a drill 400. In oneembodiment, the connector 328 is a female connector having an openingshaped (e.g., with a cross-sectional shape that is square, hexagonal,pentagonal, etc.) to receive a similarly shaped end of the shaft 410. Inanother embodiment, the connector 328 is a male connector having across-sectional shape (e.g., square, hexagonal, pentagonal, etc.)corresponding to a shape of an opening in the shaft 410 that receivesthe connector 328. Once chucked to the drill 400, the shaft 410 can berotated, which can in turn rotate the reamer 320 via the connector 328to form the cavity in the bone without rotating the elongate shaft 310,which remains in a fixed orientation in the bone.

FIG. 4 shows an embodiment of an assembly 300B that is similar to theassembly 300 in FIG. 3, except as described below. The assembly 300B isconstructed similar to the assembly 300 shown in FIG. 3, except as notedbelow. Therefore, the references numerals used to designate the variouscomponents of the assembly 300B are identical to those used foridentifying the corresponding components of the assembly 300 in FIG. 3,except that a “B” has been added to the reference numerals.

In the illustrated embodiment, the elongate shaft or stem 310B extendsat an angle α relative to an axis of the femur 10 or tibia 20 (e.g.,relative to a central axis X of the bone), where the bone (e.g., tibia)is s-shaped or to account for normal anatomy of the distal femurincluding variations of the anatomic axis in the coronal plane andfemoral bow in the sagittal plane. In one embodiment the angle α can bebetween about 3 degrees and about 5 degrees. In other embodiments, theangle α can have other values, such as between about 1 degree and about12 degrees. The proximal end 312B of the elongate shaft 310B extendsalong a vertical axis, while the portion of the elongate shaft 310Bdistal of the proximal end 312B extends at said offset angle α relativeto the vertical axis X. As with the assembly 300, the assembly 300B hasa reamer 320B that removably couples to the proximal end 312B of theelongate shaft 310B via a rotatable connection 323B (e.g., a bearingconnection, such as rolling element bearing, a boss, etc.) that allowsthe elongate shaft 310B to remain in a fixed orientation while thereamer 320B is rotated to ream a cavity into the end of the bone (e.g.,the proximal end 22 of the tibia 20). The reamer 320B is similar to thereamer 320 and operates in the same manner, can have a tapered coneshape, and can be coupled to a drill 400 via a shaft 410 that can bechucked to the drill 400 and that can couple to a connector 328B in theproximal end 324B of the reamer 320.

FIGS. 5A and 5B show a schematic side view and top view of the reamer320, 320B shown in FIGS. 3-4. The proximal end 324, 324B of the reamer320, 320B can have a surface 325, 325B that in one embodiment isgenerally planar. In other embodiments, the surface 325, 325B can haveother suitable shapes, such as concave, convex, etc. The connector 328,328B at the proximal end 324, 324B of the reamer 320, 320B in FIG. 5Bcan be female and have a generally circular shape (e.g., a cylindricalrecess) that receives the shaft 410. In other embodiments, the connector328, 328B can have other shapes (e.g., square, pentagonal, hexagonal)that mates with a similarly shaped end of the shaft 410 to allowrotation of the shaft 410 (e.g., via the drill 400) to cause rotation ofthe reamer 320, 320B. In the illustrated embodiment, the proximal end324, 324B and the distal end 322, 322B of the reamer 320, 320B canextend along substantially parallel planes, with the outer diameter ofthe proximal end 324, 324B being greater than the outer diameter of thedistal end 322, 322B to thereby define the tapered cone shape.

FIGS. 6A-6B show an embodiment of a reamer 320C that is similar to thereamer 320, 320B in FIGS. 5A-5B, except as described below. The reamer320C is constructed similar to the reamer 320, 320B shown in FIGS.5A-5B, except as noted below. Therefore, the references numerals used todesignate the various features of the reamer 320C are identical to thoseused for identifying the corresponding features of the reamer 320, 320Bin FIGS. 5A-5B, except that a “C” has been added to the referencenumerals.

In the illustrated embodiment, a proximal end 324C of the reamer 320Chas a cutout 321C so that the shape of the reamer 320C is not a completetapered cone. The cutout 321C defines a vertical surface 321C1 and ahorizontal surface 321C2 that are optionally substantially perpendicularto each other. The reamer 320C has a height 329C1 between the distal end322C and the horizontal surface 321C2 of the cutout 321C. The reamer320C has a height 329C2 between the distal end 322C and the proximal end324C. In one embodiment, the height 329C1 can be approximately one halfthe height 329C2. However, in other embodiments the ratio between theheight 329C1 and the height 329C2 can have other suitable values (e.g.,¼^(th), ⅓^(rd), ¾^(th), etc.). The cutout 321C in the reamer 320C allowsthe reamer 320C to accommodate (e.g., to not impinge on) the implant(e.g., the femoral knee implant) when implant is coupled to the reamer320C component, as further discussed below. The reamer 320C is otherwisesimilar to the reamer 320, 320B and operates in the same manner, canhave a generally tapered cone shape, and can be coupled to a drill 400via a shaft 410 that can be chucked to the drill 400 and that can coupleto a connector 328C in the proximal end 324C of the reamer 320C. Thedistal end 322C of the reamer can couple to a proximal end 312, 312B ofan elongate shaft or stem 310, 310B via a rotatable connector 323, 323B(e.g., a bearing connector, boss, etc.) that allows the reamer 320C torotate (e.g., to create the tapered cavity in the femur) while the shaft310, 310B remains in a fixed orientation (e.g., the elongate shaft 310,310B does not rotate with the reamer 320C).

FIG. 7 shows an embodiment of a reamer 320D that is similar to thereamer 320, 320B in FIGS. 3-5B, except as described below. The reamer320D is constructed similar to the reamer 320, 320B shown in FIGS. 3-5B,except as noted below. Therefore, the references numerals used todesignate the various features of the reamer 320D are identical to thoseused for identifying the corresponding features of the reamer 320, 320Bin FIGS. 3-5B, except that a “D” has been added to the referencenumerals.

In the illustrated embodiment, the reamer 320D can include one or morenested reamer portions A-D that can be sequentially coupled to eachother to define the reamer body 320D. Though FIG. 7 shows the reamer320D with four reamer portions A-D, one of skill in the art willrecognize that the reamer 320D can have any number of reamer portionsA-D, where at least a subset of the plurality of reamer portions A-D canbe fixedly coupled to each other to define the reamer 320D body. Thedistal reamer portion A can have a rotatable coupling 323D (e.g., abearing connection, such as a rolling element bearing, a boss, etc.) atthe distal end 322D that can engage an elongate element, such as theelongate element 310, 310B in FIGS. 3-4. Each of the plurality of reamerportions A-D can have a connector (e.g., female coupling) 328D at itsproximal end, which can receive a similarly shaped end of the shaft 410that can be chucked to a driving element (e.g., a drill). Each of thereamer portions A-D can have a tapered cone outer surface 326D so thatwhen two or more of the reamer portions A-D are sequentially nested, theouter surface of the reamer 320D defines a tapered cone surface. Each ofthe reamer portions A-D can also have milling elements 327D (e.g.,ridges, edges) that align with each other when two or more of theplurality of reamer portions A-D are sequentially stacked together.

The plurality of reamer portions A-D advantageously fixedly couple toeach other so that when two or more of the plurality of reamer portionsA-D are nested together to define the reamer 320D structure they move asone piece (e.g., they rotate together). For example, the plurality ofreamer portions A-D can each have one or more pins at a distal end thatextend into one or more holes in a proximal end of an adjacent reamerportion. In another embodiment, each of the reamer portions A-D can eachhave one or more holes at a distal end that receive corresponding one ormore pins in a proximal end of an adjacent reamer portion.

In use, the orthopedic surgeon could begin by using a first reamerportion (e.g., reamer portion A) to ream a cavity in a bone (e.g., inthe proximal end 22 of the tibia 20). If the surgeon determined that acavity needed to be larger, the surgeon could couple a second reamerportion (e.g., reamer portion B) onto the proximal end of the previouslyused reamer portion A to increase the size of the reamer 320D, andoperate the reamer 320D (e.g., via a drill that operatively drives thereamer 320D) to create the larger cavity size. The surgeon couldcontinue the process of nesting additional reamer portions onto thepreviously delivered reamer portions A-B, to create a cavity of thedesired size in the bone.

FIG. 8 shows an embodiment of a reamer 320E that is similar to thereamer 320C, in FIGS. 6A-6B, except as described below. The reamer 320Eis constructed similar to the reamer 320C shown in FIGS. 6A-6B, exceptas noted below. Therefore, the references numerals used to designate thevarious features of the reamer 320E are identical to those used foridentifying the corresponding features of the reamer 320C in FIGS.6A-6B, except that an “E” has been added to the reference numerals. FIG.8 shows a reamer 320E that has a tapered cone shape from the proximalend to the distal end. Once the drill 400 is disconnected from thereamer 320E, a top segment of the proximal end can be removed to definethe tapered cone with the cutout 321E. Additionally, the top segment canbe textured or colored, so the user can see where the cut-out is on eachcut-out cone reamer.

In the illustrated embodiment, the reamer 320E can include one or morenested reamer portions A′-D′, each having a proximal cutout portionA1′-D1′ that can be sequentially coupled to each other to define thereamer body 320E with a proximal cutout 321E. Though FIG. 8 shows thereamer 320E with four reamer portions A′-D′, one of skill in the artwill recognize that the reamer 320E can have any number of reamerportions A′-D′, where at least a subset of the plurality of reamerportions A′-D′ can be fixedly coupled to each other to define the reamer320E body. The distal reamer portion A′ can have a rotatable coupling323E (e.g., a bearing connection, such as a rolling element bearing, aboss, etc.) at the distal end 322E that can engage an elongate element,such as the elongate element 310, 310B in FIGS. 3-4. Each of theplurality of reamer portions A′-D′ can have a connector (e.g., femalecoupling) 328E at its proximal end, which can receive a similarly shapedend of the shaft 410 that can be chucked to a driving element (e.g., adrill). Each of the reamer portions A′-D′ can define a portion of atapered cone outer surface 326E (except where the reamer portion A′-D′has the cutout) so that when two or more of the reamer portions A′-D′are sequentially nested, the outer surface of the reamer 320E defines atapered cone surface with a proximal cutout. Each of the reamer portionsA′-D′ can also have milling elements 327 e (e.g., ridges, edges) thatalign with each other when two or more of the plurality of reamerportions A′-D′ are sequentially stacked together.

The plurality of reamer portions A′-D′ advantageously fixedly couple toeach other so that when two or more of the plurality of reamer portionsA′-D′ are nested together to define the reamer 320E structure they moveas one piece (e.g., they rotate together). For example, the plurality ofreamer portions A′-D′ can each have one or more pins at a distal endthat extend into one or more holes in a proximal end of an adjacentreamer portion. In another embodiment, each of the reamer portions A′-D′can each have one or more holes at a distal end that receivecorresponding one or more pins in a proximal end of an adjacent reamerportion.

In use, the orthopedic surgeon could begin by using a first reamerportion (e.g., reamer portion A′) to ream a cavity in a bone (e.g., inthe distal end 12 of the femur 10). If the surgeon determined that acavity needed to be larger, the surgeon could couple a second reamerportion (e.g., reamer portion B′) onto the proximal end of thepreviously used reamer portion A′ to increase the size of the reamer320E, and operate the reamer 320E (e.g., via a drill that operativelydrives the reamer 320E) to create the larger cavity size. The surgeoncould continue the process of nesting additional reamer portions ontothe previously delivered reamer portions A′-B′, to create a cavity ofthe desired size in the bone.

As with the reamer 320C, the cutout 321E of the reamer 320E allows it toaccommodate (e.g., to not impinge on) the implant (e.g., the femoralknee implant) when implant is coupled to the reamer 320E component.

FIG. 9 is an end view of a cut proximal end 22′ of the tibia 20 intowhich the reamer 320, 320B, 320D has been inserted. In one embodiment,the proximal end 324, 324B, 324D of the reamer 320, 320B, 320D can begenerally flush with the proximal surface of the cut tibia 20.Advantageously, the outer perimeter O of the reamer 320, 320B, 320D isgenerally circular and bounded by an outer boundary of cut proximal end22′ of the tibia 20.

FIG. 10 is an end view of a cut distal end 12′ of the femur 10 intowhich the reamer 320C, 320E has been inserted. In one embodiment, theproximal end 324C, 324E of the reamer 320C, 320E can be generally flushwith the distal surface 12′ of the cut femur 10. Advantageously, theouter perimeter O of the reamer 320C, 320E is generally bounded by anouter boundary of cut distal end 12′ of the tibia 20. In the illustratedembodiment, the vertical surface 321C1 of the cutout 321C, 321E facesthe anterior side of the distal end 12 of the femur 10.

FIG. 11A shows a schematic exploded view of a distal end 12 of the femur10 with the reamer 320C, 320E inserted therein, prior to attachment of atrial implant 500 on the distal end 12. Once the reamer 320C, 320E hasbeen inserted into the distal end 12 of the femur to form the desiredcavity (e.g., conical cavity), a cutting guide 600 (see FIG. 11B) can beattached to the proximal end 324C, 324E of the reamer 320C, 320E to cutthe femur 10 flush with one or more surfaces of the reamer 320C, 320E.The trial implant 500 can then be attached to the reamer 320C, 320E todefine the trial implant assembly 500′, as shown in FIG. 12. The trialimplant 500′ can be coupled with the reamer 320C, 320E in any suitablemanner (e.g., with bone cement, with one or more screws, with a splineor other mechanical attachment, slot-key connection, tapered connection,etc.). Advantageously, as seen in FIGS. 11A, 12, the cut out portion321C, 321E of the reamer 320C, 320E allows the trial implant 500 to becoupled with the proximal end 324C, 324E of the reamer 320C, 320Ewithout impinging on the trial implant 500.

FIG. 13 shows a schematic front view of the distal end 12 of the femur10 with the trial implant assembly 500′, which includes the trialimplant 500, the reamer 320C, 320E and the elongate shaft or stem 310,310B. The trial implant 500 for the femur 10 can define a pair ofcondyle surfaces 502, 504 and an anterior surface 506 that extends infront of at least a portion of the cut distal end 12 of the femur 10. Asdiscussed above, the trial implant 500 can couple to the reamer 320C,320E in any suitable manner (e.g., using screws, a spline connection,tapered connection, cement, slot and key connection, press-fitconnection, etc.).

FIG. 14 shows a schematic front view of the distal end 22 of the tibia20 with a trial implant assembly 510′, which includes a trial implant510, the reamer 320A, 320B, 320D and the elongate shaft or stem 310,310B. The trial implant 510 for the tibia 20 can extend over at least aportion of the cut proximal end 22 of the tibia 20 and can define anarticulating surface 512 that can contact the condyle surfaces 502, 504of the trial implant 500 of the femur 10. As discussed above, the trialimplant 510 can couple to the reamer 320A, 320B, 320D in any suitablemanner (e.g., using screws, a spline connection, a tapered connection,cement, slot and key connection, press-fit connection, etc.).

FIG. 15 shows one embodiment of an assembly 700 for removing an implantassembly, as further discussed below. For simplicity, the elongate shaftand implant body, as well as the bone (e.g., femur 10, tibia 20) thatthe implant is located in is not shown in FIG. 15. The implant assemblyincludes a tapered cone body 820 similar in shape to the reamer 320A,320B, 320D described above. In one embodiment, the tool 710 is a drillbit. In another embodiment, the tool 710 is a burr. In still anotherembodiment, the tool 710 is a router. The distal end 712 can have alength L that is at least as great as a height X of the tapered conebody 820. The tool 710 can be inserted between the outer surface 826 ofthe tapered cone body 820 and the bone, and the tool 710 can be operated(e.g., rotated about its axis) to detach or pry loose the tapered conebody 820 from the bone.

With continued reference to FIG. 15, the tool 710 can be inserted at anangle α1 that substantially coincides (e.g., is identical to) the angleα2 of the tapered cone body 820. A proximal end 716 of the tool 710 canbe supported at the angle α1 by a support 730 that connects the tool 710to a shaft S attached to a proximal end 824 of the tapered cone body 820by a connector 828. The tool 710 can optionally be operated manually. Inanother embodiment, the tool 710 can be operated by a power tool such asa drill 410 that couples to the proximal end 716 of the tool 710.

Though FIG. 15 shows a tapered cone body 820 that is generally similarin size and shape with the reamer 320A, 320B, 320D, the implant assemblycan instead have a tapered cone body with a cutout 820′ that is similarin size and shape as the reamer 320C, 320E described above.

FIG. 16 shows an embodiment of a kit K1 for assembling a tibial trialimplant assembly 510′ and a femoral trial implant assembly 500′. The kitK1 can include a plurality of elongate members 310, 310B of varioussizes S1-S4, a plurality of tapered cone reamers 320-320E of differentsizes A-D, and a plurality of tibial trial implants 510 and femoraltrial implants 500 of different sizes I1-I4. The surgeon would utilizethe kit K1 to assemble the desired trial implant assembly 500′, 510′ forthe femur and tibia, using different sized components, as needed toachieve the desired fit for the trail implant, as described furtherbelow in connection with FIG. 17. Once the surgeon obtained the desiredtrial implant assembly 500′, 510′, the surgeon could then assemble thefinal implant assemblies 900′, 910′ for the femur and tibia utilizing asimilar kit K2 with similarly sized components for the elongate shaft810, tapered cone body 820 and implant 900,910. Accordingly thedifferent sizes of the components of the trial implant assembly 500,510′ correlate with the different sizes of the components of the finalimplant assembly 900, 910′, simplifying the process of assembling thefinal implant assembly based on the trial implant assembly 500, 510′ thesurgeon determined was the appropriate one for the patient.

FIG. 17 is a block diagram of a method 1000 of installing a total kneeimplant. The knee implant can include a femoral implant assembly 900 anda tibial implant assembly 910 that are implanted into the distal femurand the proximal tibia, respectively. The process below is describedwith respect to implanting the tibial implant assembly 910 on the tibia20. However, a similar process is used to implant the femoral implantassembly 910, except that the tapered cone reamer with the cutout 320C,320E is used, and a similarly shaped tapered cone body 820′ is implantedonce the trial implant assembly is removed.

At block 1010, the surgeon could use a straight reamer to ream astraight cavity in the bone (e.g., the tibia 20 or femur) and then it istaken out. If the straight reamer does not point at the ankle for thetibial implant or hip for the femoral implant (e.g., has an offset of 1to 12 degrees from vertical), the surgeon would utilize a 1 to 12 degreeadapter with the straight reamer to orient the proximal tibia to theankle or distal femur to the hip.

At block 1020, the surgeon assembles the elongate shaft 310, 310B to thereamer 320A, 320B, 320D and inserts it into the straight cavity formedby the straight reamer. The elongate shaft 310, 310B provides angularorientation, while the reamer 320A, 320B, 320D provides rotational andaxial stability (e.g., via the ridges 327A, 327B, 327D on its outersurface 326A, 326B, 326D). The elongate shaft 310 in one embodiment hasa smaller outer diameter (e.g., 1-2 mm smaller) than the straight reamerto ensure the elongate shaft 310 is easily delivered into the straightcavity (e.g., does not get caught in the bone during insertion). Thesurgeon then proceeds to ream the proximal end 22 of the tibia 20 toream the tapered cone shape cavity so that it points perpendicular tothe ankle, or ream the distal end 12 of the femur 10 to ream the taperedcone shape cavity so that it points substantially perpendicular to thehip. The surgeon would continue to ream the cavity in the tibia 20 orfemur until the desired size cavity was obtained (e.g., when sufficientboney opposition and cortical contact is obtained). For example, ifusing the modular reamer 320D, the surgeon can continue to sequentiallynest reamer portions A-D of increasing size to obtain a larger taperedcone reamer body and form a larger tapered cone cavity in the tibia 20.As discussed above, the proximal end of the reamer 310A, 310B, 310D canbe coupled to a shaft that is chucked to a drill 400, which can beoperated to rotate the reamer 310A, 310B, 310D, without rotating theelongate shaft 310, 310B due to the rotatable (e.g., bearing) connectionbetween the elongate shaft 310, 310B, 310D and the reamer.

At block 1030, the surgeon can disconnect the drill 400 from theproximal end 324A, 324B, 324C of the reamer 320A, 320B, 320D once thedesired tapered cavity is achieved in the tibia 20, leaving the elongateshaft 310, 310B and the reamer 320A, 320B, 320D in place in the tibia20.

At block 1040, the surgeon can connect a cutting guide 600 to the reamer320A, 320B, 320D and cut the tibia 20 flush to the proximal end 324A,324B, 324D of the reamer 320A, 320B, 320D.

At block 1050, the surgeon can disconnect the cutting guide 600 from thereamer 320A, 320B, 320D and connect the tibial trial implant 510 todefine the trial implant assembly 510′. The surgeon would then determineif the trial implant assembly 510′ meets his or her requirements for thetibial portion of the knee implant or requires further changes (e.g.,requires a larger sized trial tibial implant 510). For example, theposition and size of the trial implant assembly 510′ can be adjusteduntil a well-balanced knee joint is achieved.

At block 1060, once the surgeon determines that the tibial trial implantassembly 510′ meets the requirements for the tibial portion of the kneeimplant, the surgeon would remove the trial implant assembly 510′ (e.g.,the tibial trial implant 510, reamer 320A, 320B, 32D and elongate shaft310, 310B) from the tibia 20.

At block 1070, the surgeon would assemble the final tibial implantassembly 910′, which would have an elongate shaft 810, a tapered cone820, and a tibial implant 910. The final tibial implant assembly 910′can be assembled in multiple pieces but is inserted into the cavity inthe tibia 20 in one piece. The elongate shaft 810 would provide axialstability, while the tapered fluted or porous cone 820 can providerotational stability (e.g., via one or more ridges that engage the bonein the cavity, such as the diaphysis).

The final tibial implant assembly 910′ is similar (e.g. identical) inshape and size as the tibial trial implant assembly 510′. For example,the elongate shaft 810 can be similar (e.g. identical) in size and shapeto the elongate shaft 310, 310B. Similarly, the tapered cone 820 can besimilar (e.g. identical) in shape and size as the reamer 320A, 320B,320C. Finally, the tibial implant 910 can be similar (e.g., identical)in size and shape as the trial tibial implant 510. The final tibialimplant assembly 910′ can differ from the tibial trial implant assembly510′ in the quality of the materials used. The surgeon can fix the finalimplant assembly 910′ in the tibia 20 utilizing any suitable method(e.g., cementing the implant assembly 910′ in the bone).

Advantageously, the size of each of the elongate shaft 310, 310B, thereamer 320A, 320B, 320D and the tibial implant 510 correspond tosimilarly sized elongate shaft 810, tapered cone 820 and tibial implant910. Moreover, the elongate shaft 310, 310B, reamer 320A, 320B, 320D andtibial implant 510 can be provided in multiple sizes, allowing thesurgeon to assembly a trial implant assembly 510′ with different sizedcomponents to achieve the desired operation from the trial implantassembly 510′. Accordingly, utilizing the trial implant assembly 510′ todetermine the desired implant arrangement simplifies the implantationprocess as the surgeon can then assemble the final implant with asimilarly sized elongate shaft, tapered cone and implant body as thetrial implant assembly 510′.

Though the method 1000 described in the steps of FIG. 16 has beendescribed with respect to the tibial implant assembly 910′ one or skillin the art will recognize that substantially the same process can beused for the implantation of the femoral implant assembly 900′. However,for the femoral implant, the reamer 320C, 320E is used instead of thereamer 320A, 320B, 320D to provide the cutout 321C, 321E to accommodatethe femoral trial implant 500 thereon, as previously described.

FIG. 18 shows one embodiment of a method 1100 for removing apre-existing implant assembly. To simplify the description, the method1100 will be described for the removal of a previously implanted tibialimplant assembly 910′ having a shape and size as described herein.However, one of skill in the art will recognize that a substantiallysimilar process can be utilized to remove a previously implanted femoralimplant assembly 900′ having a shape and size as described herein.

At step 1110, the surgeon could decouple the tibial implant 910 from thetapered cone 820.

At step 1120, the surgeon could attach the tool 710 of the removalassembly 700 to a shaft S and couple the shaft S to the tapered cone 820so that the tool 710 extends at substantially the same angle as theangle of the tapered cone.

At step 1130, the surgeon could introduce the tool 710 between the outersurface 826 of the tapered cone 820 and the bone, as illustrated in FIG.15.

At step 1140, the surgeon could operate the tool 710 (e.g. with a drill400) and rotate the tool 710 about the circumference of the tapered cone820 to disengage it from the bone about its periphery.

At step 1150, the surgeon could remove the tapered cone 820 and theelongate shaft 810 from the tibia 20, and proceed to prepare the cavityfor the implantation of a new tibial implant assembly 910′.

Advantageously, because it is only the tapered cone 820 that providesrotational stability to the tibial implant assembly 910′, is the portionof the implant assembly 910′ that is rotationally fixed to the tibia,and sits at the proximal portion of the tibial implant assembly 910′,the tool 710 does not need to be inserted to the distal end of thetibial implant assembly 910′, but rather only needs to be extended tothe distal end 822 of the tapered cone 820, which makes removal of thepreviously implanted tibial implant assembly 910′ much easier andefficient to perform, and takes less time than if the rotationalstability was also provided along a stem portion of the implant.

Accordingly, in the embodiments described herein, the height of thereamer 320-320E in the trial implant assembly 500′, 510′ andcorresponding tapered cone 820 in the final implant assembly 900′, 910′are the only portions that are rotationally fixed in the bone (femur 10,tibia 20). The elongate shaft 310, 310B in the trial implant assembly500′, 510′ and elongate shaft 810 in the final implant assembly 900′,910′ is not rotationally fixed in the bone (rather, it provides axialstability), so that the elongate shaft 310, 310B, 820 need not bedislodged from the bone by inserting a tool 710 to the distal end of theelongate shaft 310, 310B, 820. Accordingly, the tapered cone reamer320-320E and tapered cone body 820 only define a proximal portion of thetrial implant assembly 500′,510′ and final implant assembly 900′, 910′.That is, the height or length of the tapered cone reamer 320-320E of thetrial implant assembly 500′, 510′ and tapered cone body 820 of the finalimplant assembly 900′, 910′ provide a relatively small amount to thelength of the trial implant assembly 500′, 510′ and final implantassembly 900′, 910′ relative to the length of the other components(e.g., elongate shaft 310, 310B, 810). In one embodiment, the height orlength of the tapered cone reamer 320-320E of the trial implant assembly500′,510′ and tapered cone body 820 of the final implant assembly 900′,910′ is less than ½ the length of the trial implant assembly 500′, 510′and final implant assembly 900′, 910′, respectively. In anotherembodiment, the height or length of the tapered cone reamer 320-320E ofthe trial implant assembly 500′,510′ and tapered cone body 820 of thefinal implant assembly 900′, 910′ is less than ⅓ the length of the trialimplant assembly 500′, 510′ and final implant assembly 900′, 910′,respectively. In still another embodiment, the height or length of thetapered cone reamer 320-320E of the trial implant assembly 500′,510′ andtapered cone body 820 of the final implant assembly 900′, 910′ is lessthan ¼ the length of the trial implant assembly 500′, 510′ and finalimplant assembly 900′, 910′, respectively.

While certain embodiments of the inventions have been described, theseembodiments have been presented by way of example only, and are notintended to limit the scope of the disclosure. Indeed, the novel methodsand systems described herein may be embodied in a variety of otherforms. Furthermore, various omissions, substitutions and changes in thesystems and methods described herein may be made without departing fromthe spirit of the disclosure. For example, one portion of one of theembodiments described herein can be substituted for another portion inanother embodiment described herein. The accompanying claims and theirequivalents are intended to cover such forms or modifications as wouldfall within the scope and spirit of the disclosure. Accordingly, thescope of the present inventions is defined only by reference to theappended claims.

Features, materials, characteristics, or groups described in conjunctionwith a particular aspect, embodiment, or example are to be understood tobe applicable to any other aspect, embodiment or example described inthis section or elsewhere in this specification unless incompatibletherewith. All of the features disclosed in this specification(including any accompanying claims, abstract and drawings), and/or allof the steps of any method or process so disclosed, may be combined inany combination, except combinations where at least some of suchfeatures and/or steps are mutually exclusive. The protection is notrestricted to the details of any foregoing embodiments. The protectionextends to any novel one, or any novel combination, of the featuresdisclosed in this specification (including any accompanying claims,abstract and drawings), or to any novel one, or any novel combination,of the steps of any method or process so disclosed.

Furthermore, certain features that are described in this disclosure inthe context of separate implementations can also be implemented incombination in a single implementation. Conversely, various featuresthat are described in the context of a single implementation can also beimplemented in multiple implementations separately or in any suitablesubcombination. Moreover, although features may be described above asacting in certain combinations, one or more features from a claimedcombination can, in some cases, be excised from the combination, and thecombination may be claimed as a subcombination or variation of a subcombination.

Moreover, while operations may be depicted in the drawings or describedin the specification in a particular order, such operations need not beperformed in the particular order shown or in sequential order, or thatall operations be performed, to achieve desirable results. Otheroperations that are not depicted or described can be incorporated in theexample methods and processes. For example, one or more additionaloperations can be performed before, after, simultaneously, or betweenany of the described operations. Further, the operations may berearranged or reordered in other implementations. Those skilled in theart will appreciate that in some embodiments, the actual steps taken inthe processes illustrated and/or disclosed may differ from those shownin the figures. Depending on the embodiment, certain of the stepsdescribed above may be removed, others may be added. Furthermore, thefeatures and attributes of the specific embodiments disclosed above maybe combined in different ways to form additional embodiments, all ofwhich fall within the scope of the present disclosure. Also, theseparation of various system components in the implementations describedabove should not be understood as requiring such separation in allimplementations, and it should be understood that the describedcomponents and systems can generally be integrated together in a singleproduct or packaged into multiple products.

For purposes of this disclosure, certain aspects, advantages, and novelfeatures are described herein. Not necessarily all such advantages maybe achieved in accordance with any particular embodiment. Thus, forexample, those skilled in the art will recognize that the disclosure maybe embodied or carried out in a manner that achieves one advantage or agroup of advantages as taught herein without necessarily achieving otheradvantages as may be taught or suggested herein.

Conditional language, such as “can,” “could,” “might,” or “may,” unlessspecifically stated otherwise, or otherwise understood within thecontext as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements, and/or steps. Thus, such conditional language is notgenerally intended to imply that features, elements, and/or steps are inany way required for one or more embodiments or that one or moreembodiments necessarily include logic for deciding, with or without userinput or prompting, whether these features, elements, and/or steps areincluded or are to be performed in any particular embodiment.

Conjunctive language such as the phrase “at least one of X, Y, and Z,”unless specifically stated otherwise, is otherwise understood with thecontext as used in general to convey that an item, term, etc. may beeither X, Y, or Z. Thus, such conjunctive language is not generallyintended to imply that certain embodiments require the presence of atleast one of X, at least one of Y, and at least one of Z.

Language of degree used herein, such as the terms “approximately,”“about,” “generally,” and “substantially” as used herein represent avalue, amount, or characteristic close to the stated value, amount, orcharacteristic that still performs a desired function or achieves adesired result. For example, the terms “approximately”, “about”,“generally,” and “substantially” may refer to an amount that is withinless than 10% of, within less than 5% of, within less than 1% of, withinless than 0.1% of, and within less than 0.01% of the stated amount. Asanother example, in certain embodiments, the terms “generally parallel”and “substantially parallel” refer to a value, amount, or characteristicthat departs from exactly parallel by less than or equal to 15 degrees,10 degrees, 5 degrees, 3 degrees, 1 degree, or 0.1 degree.

The scope of the present disclosure is not intended to be limited by thespecific disclosures of preferred embodiments in this section orelsewhere in this specification, and may be defined by claims aspresented in this section or elsewhere in this specification or aspresented in the future. The language of the claims is to be interpretedbroadly based on the language employed in the claims and not limited tothe examples described in the present specification or during theprosecution of the application, which examples are to be construed asnon-exclusive.

1. (canceled)
 2. A method for removing an implant assembly, the methodcomprising: mechanically supporting a tool relative to the implantassembly so that the tool is oriented at an angle corresponding to anangle defined by at least a portion of an outer surface of an implantbody fixed in a bone; linearly advancing the tool relative to theimplant to introduce at least a portion of the tool into an interfacebetween the at least a portion of the outer surface of the implant bodyand the bone to detach the implant body from the bone; and removing theimplant assembly from the bone.
 3. The method of claim 2, wherein thetool is maintained at the angle while linearly advancing the toolrelative to the implant.
 4. The method of claim 2, further comprisingrotating the tool about the at least a portion of the outer surface ofthe implant body while in the interface to disengage the implantassembly from the bone.
 5. The method of claim 2, wherein the implantbody comprises a tapered body.
 6. the method of claim 5, wherein thetapered body comprises a tapered cone body.
 7. The method of claim 6,wherein the tool is a burr.
 8. The method of claim 2, wherein the toolis a drill bit.
 9. The method of claim 2, wherein the tool is a router.10. The method of claim 2, wherein the tool comprises a length of atleast as great as a height of the implant body.
 11. A removal assemblyfor removing an implant assembly, the removal assembly comprising: oneor more tools, each tool comprising a proximal end and a distal end, thedistal end configured to be inserted between at least a portion of anouter surface of the implant assembly and a bone; and a supportconfigured to position and advance the one or more tools at apredetermined angle aligned with an angle of the at least a portion ofthe outer surface of the implant assembly.
 12. The removal assembly ofclaim 11, the support further configured to rotate the tool about alongitudinal axis of the tool while the support maintains the tool in afixed position at the predetermined angle.
 13. The removal assembly ofclaim 11, wherein the implant body comprises a tapered body.
 14. theremoval assembly of claim 13, wherein the tapered body comprises atapered cone body.
 15. The removal assembly of claim 11, wherein thetool is a burr.
 16. The removal assembly of claim 11, wherein the toolis a drill bit.
 17. The removal assembly of claim 11, wherein the toolis a router.
 18. The removal assembly of claim 11, wherein the toolcomprises a length of at least as great as a height of the implant body.19. A removal assembly for removing an implant assembly, the removalassembly comprising: an tool comprising a proximal end and a distal end,the distal end configured to be inserted between at least a portion ofan outer surface of the implant assembly and a bone; and a support thatextends between a first end and a second end, the support being attachedat the first end to the proximal end of the tool, the support beingattached at the second end to a portion of the implant assembly, whereinthe support allows the tool to rotate about a longitudinal axis of thetool while the tool remains in a substantially fixed angularorientation, wherein the substantially fixed angular orientation isaligned with an angle of the at least a portion of the outer surface ofthe implant assembly.
 20. The removal assembly of claim 19, wherein theimplant body comprises a tapered body.
 21. the removal assembly of claim20, wherein the tapered body comprises a tapered cone body.
 22. Theremoval assembly of claim 19, wherein the tool comprises a length of atleast as great as a height of the implant body.